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Biology

Abstract

Understanding the influence of weather on reproductive events is critical for documenting population demographics and developing appropriate conservation and management strategies. Variations in timing of parturition may be due to changes in the ambient weather which affect the available insect prey density and time reproductive bats must spend torpid. Capture data from 6,767 bats representing 12 species from 28 counties and 360 sites, were used to examine the influence of precipitation, temperature, and latitude on reproduction of bats in Missouri. Although both cool springs and heavy spring precipitation delayed the onset of each reproductive condition, temperature had a greater influence on reproductive timing. Contrary to predictions, high spring precipitation increased reproductive rate and increased synchrony in dates of pregnancy. Differences in onset of reproduction between northern and southern Missouri were not significant, although capture of juveniles ended sooner in northern Missouri. There was a difference in peak nightly activity among bats of different reproductive conditions for all species except Indiana bats, which had a later interspecific activity peak. Red bats had a female biased juvenile sex ratio especially early season, northern bats and gray bats were male biased. Five species had adult male biased sex ratios. Lactating female big brown bats have a lower mass in years with cooler springs. The inevitable escalation of climatic extremes may cause Midwestern bat species to experience environmental stressors in different ways. These data provide regional managers with better tools to address seasonal Indiana bat survey guidelines and potentially inform seasonal mitigation of wind energy facilities based on annual weather variation.